Anadromous or Catadromous?

Here's a quiz question: what's the difference between an anadromous fish and a catadromous fish? If you know, move along to the next blog and try not to be smug with the rest of us because I didn't know the difference until a few moments ago when I was scrolling down this glossary of fish-related terms.

I was thinking about adding the glossary to the right hand links but I think it's just a bit too scientific in some respects and a bit obvious in others. I don't need to have sand defined for me.

Anyway for the record, salmon and sea trout are anadromous because they reproduce in fresh water and migrate to the sea in order to feed and grow. The common eel, on the other hand, is catadromous because it migrates from rivers to spawning grounds in the sea. So now I know.

This is possibly a more useful glossary for anyone just starting out in fly fishing.